Notes from the field: Hurricane Sandy passes through Millbrook

Tuesday, February 26, 2013

The Cary Institute's Environmental Monitoring Station has collected weather data continuously since 1988. Its instruments track air pollution, precipitation patterns, and solar radiation, among other things. These measurements are essential to evaluating the impacts of climate change and the success of pollution control measures. They also provide a window into powerful storm systems, like Hurricane Sandy.

The conditions Hudson Valley citizens experienced as Sandy approached on October 29th were recorded in precise detail by our Environmental Monitoring Station. Victoria Kelly, the station's manager, noted that the relationship between wind direction and barometric pressure was particularly dynamic.

At about 1 a.m. on the 29th, wind blew steadily from the north-northeast at approximately 10 mph; at the same time the barometric pressure began falling. The eye of the storm was closest to Millbrook between 6 p.m. and 7 p.m., when the eye moved over Atlantic City, some 200 miles to the south. In that short time frame, the wind dropped and changed direction, and the lowest barometric pressure readings were recorded.

“If you look at the satellite photo of the storm, you can see that the wind is from the north-northeast before the eye wall passes by, and then from the southeast afterward,” Kelly commented. “The wind direction switches almost exactly when the barometric pressure hit bottom.”

Those venturing outside at this time may have noticed a period of warmer, more humid weather as a result of those southeasterly winds. And as the eye of the storm moved away, residents might have felt or heard Sandy's major gusts. The strongest winds measured on our campus were 52 mph at 8:27 p.m.

Although the storm’s eye didn't pass directly over Millbrook, the area experienced a typical pattern of increased winds from the backside of the storm. “The most surprising aspect of Sandy was the small amount of rainfall we received—only 0.43 inch of rain, which was far less than was forecast for the area,” comments Kelly. “Because of the way the storm tracked, we were relatively spared.”

Happily, Kelly did not have to don foul-weather gear to take readings. Thanks to data feeds from state-of-the-art remote sensors, she was able to access storm measurements safely from her home computer.